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Abdou L. Dieng, Saidou M. Sall, Laurence Eymard, Marion Leduc-Leballeur, and Alban Lazar

tropical Atlantic . Mon. Wea. Rev. , 97 , 716 – 726 , doi: 10.1175/1520-0493(1969)097<0716:SROADA>2.3.CO;2 . 10.1175/1520-0493(1969)097<0716:SROADA>2.3.CO;2 Chen , S.-H. , and Y.-C. Liu , 2014 : The relation between dry vortex merger and tropical cyclone genesis over the Atlantic Ocean . J. Geophys. Res. Atmos. , 119 , 11 641 – 11 661 , doi: 10.1002/2014JD021749 . 10.1002/2014JD021749 Chen , T.-C. , 2006 : Characteristics of African easterly waves depicted by ECMWF reanalyses for 1991

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Elinor R. Martin and Chris Thorncroft

1. Introduction African easterly waves (AEWs) are the dominant synoptic weather systems to impact rainfall across the Sahel during the West African monsoon (WAM; see Kiladis et al. 2006 , and references therein). In addition to impacting Sahel rainfall, AEWs play an important role in Atlantic tropical cyclone (TC) development. While not all AEWs lead to the formation of a TC, approximately 60% of all Atlantic TCs and 80% of all major hurricanes form in association with AEWs ( Landsea 1993

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Kerry H. Cook and Edward K. Vizy

Ocean dipole model of SST anomalies. Kabanda and Jury (1999) find that east–west SSTA gradients in the tropical Indian Ocean are associated with an anomalous zonal circulation that enhances convection over the western ocean basin and northern Tanzania. Zorita and Tilya (2002) find that variations in the long rains in March and April are also accompanied by zonal wind anomalies but, in May, they are associated with meridional surface temperature structures that suggest a correlation with the

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Rosalind Cornforth, Douglas J. Parker, Mariane Diop-Kane, Andreas H. Fink, Jean-Philippe Lafore, Arlene Laing, Ernest Afiesimama, Jim Caughey, Aida Diongue-Niang, Abdou Kassimou, Peter Lamb, Benjamin Lamptey, Zilore Mumba, Ifeanyi Nnodu, Jerome Omotosho, Steve Palmer, Patrick Parrish, Leon-Guy Razafindrakoto, Wassila Thiaw, Chris Thorncroft, and Adrian Tompkins

—coastal regions, central Africa, and the eastern Sahel as a source of intraseasonal variability affecting West Africa. Further study of the forcing by, and interactions with, midlatitude and equatorial waves, and the Indian monsoon. Extending research to other seasons, in particular, spring and the corresponding heat waves, and to the pre-onset of the monsoon. Coupling with the ocean, in particular, cold tongue development and its impact on the monsoon. More attention on radiation processes, clouds, and

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Wassila M. Thiaw and Vadlamani B. Kumar

in agricultural production and river flow. The National Oceanic and Atmospheric Administration (NOAA)’s Climate Prediction Center (CPC) began to provide USAID FEWS with real-time gauge-based 10-day weather summaries to enable operational monitoring of crop conditions. However, given the difficulty to access rain gauge measurements from Africa, CPC also began to provide USAID FEWS with access to real-time satellite rainfall estimates to improve the weather summaries and to enable effective

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M. Issa Lélé, Lance M. Leslie, and Peter J. Lamb

Atlantic Ocean contributes the most to rainfall over western Sahel, whereas the Gulf of Guinea and the South Atlantic Ocean contribute the most over the central Sahel. Local evaporation is the second largest contributor to rainfall for both regions. Long et al. (2000) examine the large-scale forcing mechanisms in relation to initiation and maintenance of the Sahelian long-term drought. They analyzed rainfall, moisture flux, and vertical motion data and concluded that changes in the general circulation

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Thomas Engel, Andreas H. Fink, Peter Knippertz, Gregor Pante, and Jan Bliefernicht

characteristics and hitherto poorly documented atmospheric dynamics of these events. Only the Ouagadougou rainfall event is briefly discussed in Cornforth et al. (2017) as an example of an African easterly wave (AEW) breaking event, and a synoptic overview is given in Galvin (2010) . The paper is structured as follows. Section 2 gives a detailed description of the gauge, satellite, and reanalysis data used in this study, including their advantages and limitations. Section 3 describes the methods to

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Lisa Hannak, Peter Knippertz, Andreas H. Fink, Anke Kniffka, and Gregor Pante

1. Introduction The weather and climate in West Africa are characterized by the West African monsoon (WAM) system. During boreal summer differential heating of land and ocean together with upwelling of colder waters create a marked horizontal pressure gradient between the Saharan heat low (SHL) and the tropical Atlantic Ocean, which drives the southwesterly monsoonal flow ( Eltahir and Gong 1996 ; Hall and Peyrillé 2006 ). The WAM circulation controls winds, temperature, clouds, and most

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Robert A. Clark III, Zachary L. Flamig, Humberto Vergara, Yang Hong, Jonathan J. Gourley, Daniel J. Mandl, Stuart Frye, Matthew Handy, and Maria Patterson

the development of new hydrological modeling software: EF5. EF5 is a framework encompassing multiple hydrological model cores, including but not limited to the grid cell–based water balance component of CREST, linear reservoir routing as implemented in CREST, routing using the kinematic wave assumption ( Chow et al. 1988 ), and the Sacramento family of water balance models ( Burnash et al. 1973 ). EF5 accepts the same input file formats as the CREST model and adds support for GeoTIFF (tagged image

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Peter J. Lamb, Diane H. Portis, and Abraham Zangvil

1. Introduction Central to atmospheric behavior on a range of space and time scales is the relative importance of horizontal water vapor advection versus the vertical moisture flux from the earth’s land and ocean surfaces. At the small-scale extreme, the interaction of these moisture sources and their associated thermodynamic and dynamic processes contributes to the development of shallow cumulus clouds (e.g., Krishnamurti et al. 1980 ; Rabin et al. 1990 ; Chen and Avissar 1994 ; Berg and

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